Semiconductor devices, for example, fast recovery diodes ("FRED"s) are well known and are a hybrid of Schottky diodes and PN diodes. This arrangement produces a lower forward voltage drop at higher current, along with a higher switching speed than is available in only a PN junction diode or only a Schottky diode. In the present manufacture of such FRED devices, a plurality of spaced P diffusions of any desired topology are formed in an N type wafer. A contact layer of aluminum overlies the full upper surface of the silicon, except for a termination area. PN junction diodes are then formed where the aluminum contacts the surface of a P diffusion and a Schottky diode is formed where the aluminum contacts the N silicon surface between spaced P diffusions.
The topology of the P diffusion can be spaced polygonal annuli, stripes, or the like. The periphery of the die is then surrounded by a termination region.
The manufacturing process for such FREDs has been complicated by a need for 3, 4, 5 or 6 mask steps during the processing of the device. These mask steps are used to define the termination pattern, the P diffusion pattern and the final metallization pattern. The use of a large number of mask steps increases the cost of the final device and is a source of device defects.
It would be desirable to provide a manufacturing process for a FRED and its termination which uses fewer mask steps without sacrificing device quality. It is also desirable to be able to provide a novel terminal structure for any semiconductor device which provides increased breakdown voltage without the need for a large number of mask steps.